Today there is a great need for stationary marine structures located in and above bodies of water. Examples of such structures include offshore platforms, boat ports, oil wells and mining rigs. Many are essentially man-made islands.
Many of the marine structures are sealed for buoyancy prior to launching into the body of water. Although sealed, controlled flooding of the structures is usually required to properly upright and set the structures. Conventional methods of controlling the flooding include reach rod systems and hydraulic systems.
Reach rod systems include a series of interconnected, jointed rod segments, a valve, and an actuator lever. The valve is attached to the marine structure below the water line. The valve controls the flow of water into the sealed structure. The rod segments are attached to the valve and extend to a point above the water level. There, a rod segment is attached to a lever or handle. By rotating the lever or handle the valve is actuated.
Reach rod systems, while jointed are essentially rigid, and proper alignment during construction is critical. Proper alignment is especially critical where the rod segments must be arranged to avoid braces, anodes and other obstructions disposed between the valve and the lever. Even though properly aligned, reach rods sometimes bind leaving the system inefficient or useless. Also, reach rod systems are limited in length because the gravitational forces on the heavy rods also can cause binding.
Hydraulic systems for flooding marine structures include a valve connected to a hydraulic pump. Like the reach rod system, the valve is attached to the structure below the water level. The hydraulic pump and its controls are ordinarily located above the water level on the work deck. A fluid line couples the pump with the valve actuator and serves to communicate hydrualic fluid to operate the valve.
In most cases, well trained technicians are required to install, test and operate the hydraulic systems. Furthermore, hydrualic systems provide no direct indication to the operator of valve position without additional instrumentation.
The above recited problems associated with reach rod systems and hydraulic systems are not intended to be exhaustive; instead, they are enumerated for the purpose of demonstrating the need for a better system for use in flooding submersible marine structures.